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2차원 후방계단유동에 대한 URANS와 DES의 수치해석 평가
송지수(C.S. Song),박승오(S.O. Park) 한국전산유체공학회 2006 한국전산유체공학회지 Vol.11 No.2
A two-dimensional backward facing step flow is simulated by using URANS and Detached Eddy Simulations(DES) approaches. Turbulence models adopted for URANS and DES simulations are Spalart-Allmaras(S-A) model and Shear Stress Transport(SST) model. The target flow with ER=1.125, Re <SUB>H</SUB>=37,500 is experimentally studied by Driver & Seegmiller. Various versions of DES have been tested in this paper. Results of the simulations are compared with the experimental data available to evaluate the merits and demerits of URANS and several versions of DES. URANS simulation converges to a steady state and hence unsteady characteristics are not featured. DES simulations in general successfully mimic large scale structures and oscillation characteristics of the flow.
김성인(S.I. Kim),박승오(S.O. Park),홍승규(S.K. Hong),이광섭(K.S. Lee) 한국전산유체공학회 2005 한국전산유체공학회지 Vol.10 No.4
Present study simulates oscillatory supersonic impinging jet flows using the axisymmetric Navier-Stokes code. To capture the salient features of flow oscillation and overcome the divergence during the initial transient period, several tests have been conducted for the grid and time step sizes. The results also show that the effects of the inlet flow condition at the nozzle exit and turbulence on the oscillatory behavior of supersonic impinging jets are negligible. Frequencies of the surface pressure oscillation obtained by the selected numerical method are in good accord with the measured impinging tones for various cases of nozzle-to-plate distance. Two seemingly different staging behaviors with nozzle-to-plate distance and nozzle pressure variations are found to correlate well if the frequency and distance are normalized by the length of the first shock cell.
Hybrid RANS/LES 방법을 이용한 아음속 공동 유동의 수치적 모사
장경식(K. S. Chang),박승오(S. O. Park),최석기(S. K. Choi) 한국전산유체공학회 2004 한국전산유체공학회지 Vol.9 No.2
A numerical simulation of an incompressible cavity flow is conducted using the hybrid turbulence model. The model adopted is a modified type of DES using k-ε two-equation model. Cavity geometry and flow condition are based on Cattafesta's experiment. Computational results are compared with the results of Cattafesta's experiment. The simulation successfully predicts the oscillatory features and the Strouhal number of the oscillation compares very favorably with that of the dominant mode of experimental data. Vorticity contours obtained from the simulation data are consistent with the smoke visualization of the Cattafesta's experiment. The coherent structures of cavity flow are also investigated using Q criterion.
DES 방법을 이용한 비압축성 열린 공동 유동의 수치적 모사
장경식(K.S. Chang),박승오(S.O. Park),권오준(O.J. Kwon),G. Constantinescu 한국전산유체공학회 2005 한국전산유체공학회지 Vol.10 No.3
Three-dimensional incompressible flow past an open cavity in a channel is investigated using Detached Eddy Simulation(DES). The length to depth ratio of the cavity is 2 and the Reynolds number defined with the cavity depth is 3,360. The DES methods are based on the Menter's SST model. In the present work, two types of inflow conditions are used; one is RANS profile, the other is LES inflow from another Large Eddy Simulation(LES) of fully developed channel flow. The results are compared with experimental data and LES results in terms of the mean statistics, temporal physics and scalar transport phenomenon of the flow.